1. Field of the Invention
The present invention relates to an information display apparatus used for an output terminal of an information processing system.
2. Description of the Prior Art
In recent years, information communications technology has made rapid progress, such as optical communication, information network system (INS) and value-added network (VAN). With the progress of such communications technology, information output terminal equipment has been developed. Utilized as the output terminal equipment and vigorously developed these days are soft copies represented by CRTs and liquid-crystal displays (LCDs) and hard copies such as printers.
Since the CRTs and LCDs themselves have no storage function, the amount of information which can be displayed in one frame without dazzling the human eyes is limited. In particular, flat-plate type displays using a liquid crystal or the like have the following problems (although they can be reduced overall size in contrast to the CRT displays). Namely, since the flat-plate type displays are driven by means of matrix electrodes, an increase in the amount of information displayed in one frame causes an increase in the number of required drive circuits, resulting in exceedingly high costs.
On the other hand, output apparatuses such as printers are capable of recording (although the information display speed thereof is relatively slow). Therefore, these output apparatuses provide a satisfactory information display capacity per frame and a relatively high resolution. However, it is necessary to carry out maintenance of expendable supplies, such as ink, toner and the like, and such devices do not enable rewriting of a hard copy on which information has already been output.
As described above, conventional information output terminal apparatuses include those which enable rewriting of information but per se possess no memory function and therefore have a relatively small information display capacity per frame and unsatisfactory resolution, such as CRTs and LCDs, and those which can record and hold information but need maintenance and do not enable rewriting of information, such as printers. As a means which has the functions of both of the above-described two types of information output terminal apparatuses, a sheet which enables writing of information using electrophoresis has already been proposed (A. Chiang, D. Curry, M. Zarzychi: A Stylus Writable Electrophoretic Display Device., SID 79 Digest, pp. 45-46 (1979)), but this cannot be put into practical use because of its complicated structure.